Switched on days ago and all set for first night of the Proms.
Immediately apparent that sound was not stereo. Checked cable (wiggle test), signal green light is on, no stereo lamp tuned to 90.5 (R3).
Signal is from a G17, directed at the Sutton Coldfield transmitter. So dialling across the main beeb stations and CFM, 88.3 and 90.5 (R3) are not being processed by NAT01 in stereo, while 97.9 (R1) and 100.1 (CFM) are.
Cross reference to my NAT02 in my NC2 system, stereo is showing on 90.5.
That suggests the feed is good, which from aerial is split, one direct to NAT01, the other to an aerial amplifier which in turn feeds the rest of the house including NAT02.
Iirc the tuner heads can go adrift at lower ferquencies, but that is as far as I remember.
Perhaps @Mike-B and @NeilS might be able to suggest what else to check?
The NAT01 is a 1997 unit serial number 197***, last serviced in 2016. The unit, unlike my active system, is only powered up periodically.
The NAT02 is a 1999 unit serial number 153***, service history unknown, purchased from a Naim dealer two or so years ago (find the stream delay too frustrating from beeb iradio).
edit - Just tried a different fly lead, between the coax wall plate and the NAT01 head unit - no difference, higher freq ok, lower no stereo!
Overnight left the NAT01 powered up.
This morning unplugged NAT02 and in my main system room, spotted that the NAT01 was brighter and both green arrows illuminated.
Clearly NAT01 was not going to be usurped by an 02!
Thanks to @Skeptikal and @davidhendon for the suggestion. It was a move I had put off, because it is at the bottom of fraim stack 1, usually placed on the glass before building the stack up.
Checked the beeb transmitter update, nothing specific, although there had been a partial fault, but no details on R3.
Pure conjecture, but it may have been that the power was lower, such that 01 - direct aerial feed wasn’t enough, while the 02 fed via a Labgear amplifier boosted it just enough. Difficult to tell, but both tuners seem brighter today than y’day, which may indicate full signal has returned?
Neil, thanks very much for prompt response, details in post above, both lights now returned on 01, after being left on overnight. The unit when reported, hadn’t just been switched on!
Twenty four hours on and the two green lights are again not showing on NAT01.
Tried a Quad FM4, which iirc @davidhendon uses.
Photo below, shows tuner connected to the direct aerial feed, in lieu of NAT01.
It shows 6 bars and Stereo - perhaps DH recalls whether that is the maximum?
By contrast when connected to the amplified feed at the other end of the house, usual connection is NAT02, it is one bar less after a long run of coax.
Looks like a return visit to the factory, perhaps @NeilS would be kind enough to confirm?
I would still try the 02 on that feed while the 01 is displaying the problem, as they share the same tuner head.
In my experience, the 101, 01 & 02 are somewhat fussy when it comes to signal.
We have a particular “mediocre” feed at the factory which the above aren’t very happy with, but an 03/05 is fine.
My FM4 is boxed up and in the loft. I have two NAT 05 XS tuners that are currently in use. The signal strength display of the FM4 varies by version of the FM4. But that does sound about right.
Anyway as Neil says, or paraphrasing it, if the NAT02 is ok when substituted on the feed for the NAT01 when it’s failing, then you probably will have your answer.
Naim excel - thanks to all, including @NeilS and PB for signing off the test sheet.
In as little as two weeks turnaround, the NAT01 has been down to HQ, been on the bench, tested and returned. The report states, Tuner head misaligned, replaced the FETs and trimmer.
Two days on, all still showing full green lights (sounds like a cockpit check for landing).
Sound back to as good as ever fed by a G17.
All too often certain negativity on the forum from some quarters, so here, a sincere thank you to Naim staff (and dealer). Great news that a unit made nearly thirty years ago, with production ceased only slightly more recently, has been brought back to spec.
